docs: clean up waveform-codec doc layers per review

Three "truth layers" had drifted apart between commits.  Fixed:

1. waveform_codec.py docstring rewritten from the 2026-05-08
   "structural framing only" state to the 2026-05-11 "Tran segment 0
   solved + segment-header partially decoded" state.  Killed stale
   "~80 sample-sets per segment" language (real segments are
   flash-page-byte-sized, not sample-count-sized; observed first-segment
   sizes are 42-510 samples depending on signal).  Killed stale
   "preamble is 7 or 9 bytes" language (always 7).

2. docs/instantel_protocol_reference.md §7.6.1: added a clear
   "CURRENT STATUS" box at the top with a status table.  Replaced the
   stale "~80 sample-sets" line with the verified per-event segment
   sizes.  Merged two redundant segment-header field-table sections.

3. docs/waveform_codec_re_status.md (NEW): clean working-status doc.
   Solved / not solved / hypothesis / next experiment / fixtures /
   tests.  The protocol reference remains the historical Rosetta
   Stone; this new file is the current-truth working note that
   shouldn't accumulate fossil layers.

4. CLAUDE.md §"Waveform body codec": prominent warning box at top —
   "DO NOT TRUST decoded sample arrays yet."  BW binary passthrough
   is the only sample-bearing output to trust until the decoder
   lands.  Added a "Next experiment" subsection pointing the next
   pass at the segment-channel scoring analyzer.

40 tests still pass.

CLAUDE.md

@@ -61,10 +61,24 @@ Full read pipeline + write pipeline + erase pipeline + monitor log + call home c
 
 ## Waveform body codec — PARTIAL (2026-05-11)
 
+> ### ⛔️ DO NOT TRUST decoded sample arrays yet
+>
+> `client.py:_decode_a5_waveform` still uses the broken legacy int16 LE
+> decoder.  The `.h5` sidecars SFM writes contain WRONG sample values
+> for every event.  Treat decoded sample arrays as "unverified" in all
+> downstream consumers.
+>
+> The **BW binary write path** (`blastware_file.py`) is unaffected —
+> it's pure passthrough of device flash bytes and remains byte-perfect.
+> Use the `.bw` binary as the authoritative waveform output until the
+> codec is fully decoded.
+>
+> Clean working-status doc: `docs/waveform_codec_re_status.md`.
+> Full archaeological record: `docs/instantel_protocol_reference.md §7.6.1`.
+
 The **per-byte decoding** of the Blastware waveform-file body (between the
 21-byte STRT record and the 26-byte footer) was historically claimed to be
-"raw int16 LE, 8 bytes per sample-set."  That was wrong — see the
-retraction in `docs/instantel_protocol_reference.md §7.6.1`.  The body
+"raw int16 LE, 8 bytes per sample-set."  That was wrong.  The body
 is actually a tagged-block stream with a custom delta+RLE codec.
 
 ### What's solved (2026-05-11)
@@ -96,13 +110,26 @@ is actually a tagged-block stream with a custom delta+RLE codec.
   (SS0, SV0) and breaks the simple Tran walk there.  Probably a channel-
   switch or alternative-encoding marker for high-amplitude regions.
 
+### Next experiment
+
+**Don't hero-code the full decoder.**  Build a small analysis tool — a
+segment-channel scoring analyzer.  For each segment of each fixture
+event, run the segment-0 Tran block-walk + RLE decode and score the
+cumulative trajectory against the BW ASCII truth for each of {Tran,
+Vert, Long, MicL} over that segment's sample range, trying different
+anchor-bytes candidates from the segment header.  The winning
+(channel, anchor-location) combination for each segment reveals
+whether segments rotate channels and which header bytes encode the
+per-segment channel anchors.
+
+See `docs/waveform_codec_re_status.md` for the full specification of
+the next experiment.
+
 ### Production-code status
 
 `client.py:_decode_a5_waveform` still uses the old (broken) int16 LE
-decoder.  Until the multi-channel decoder lands, the `.h5` sidecars
-produced by SFM contain WRONG samples — keep treating them as
-"unverified" downstream.  `decode_waveform_v2()` returns `None` as a
-placeholder.
+decoder (see warning at the top of this section).  `decode_waveform_v2()`
+in `minimateplus/waveform_codec.py` returns `None` as a placeholder.
 
 ### Test fixtures